Known in the art is a silver-based alloy consisting of 70% by weight of silver and 30% by weight of palladium (cf. TGC 12736, GDR Standard).
This alloy, however, is used only for the manufacture of rivet and stud contacts. The low level of elastic properties of this alloy does not enable its use for the manufacture of flexible-contact members. Furthermore, contacts manufactured from this alloy have a low erosion resistance.
Known in the art are contact-spring multi-component alloys based on expensive noble metals--gold and platinum.
Such alloys have the following composition, % by weight: 1. gold--72, copper--14, silver--4, platinum --9, zinc--1.2. palladium--35, silver--30, platinum--10, gold--10, copper--14, zinc--1. (cf. C. K. Barker, Product Engineering, 1964, 35, No. 10, p. 62).
These alloys possess a good combination of electrocontact and elastic properties. However, a high specific electrical resistance and insufficient thermal conductivity of these alloys restrict fields of their application. Furthermore, the procedure of production of these alloys is rather complicated and labour-consuming. An essential disadvantage also resides in the presence of expensive noble metals--gold and platinum--in their compositions.
Known in the art are less-alloyed contact-spring alloys based on silver reinforced by an internal oxidation (oxidizing heat-treatment) incorporating, % by weight: magnesium--0.3, nickel--0.2, silver--the balance (cf. U.S. Pat. No. 3,117,894 of Jan. 14, 1964; Cl. 148-11.5) or palladium--20, magnesium--0.3, silver--the balance (USSR Inventor's Certificate No. 291980, "Bulletin for Discoveries, Inventions, Industrial Designs and Trademarks", No. 4, 1971, p. 85, Cl. C 22 c, 5/06) at a satisfactory level of durability, flexibility and electrocontact properties possess a low plasticity after internal oxidation (relative elongation does not exceed 4%). This substantially reduces the service life of springs made therefrom under cyclic loads and does not provide for the possibility of internally oxidized semi-finished articles (bands and wire) from these alloys for the manufacture of monometallic contacts and bimetals.
Furthermore, the prior art silver-based alloy incorporating magnesium and nickel has a low corrosion resistance in sulphur-containing media.